THE PHOTOGRAPHIC NEWS, September 24, 1858, p.33

BLACK AND WHITE POSITIVES ON ALBUMENISED PAPER.

Glasgow, 14th September, 1858.

Sir,--Your new work entitled the "PHOTOGRAPHIC NEWS" has induced me to write you on Albumen Positive Printing. I may premise I have been a reader of Notes and Queries, London and Liverpool Photographic Journals, Notes, &ç. &c., from the first, and have endeavoured to pick up such formula as would, on albumenised paper, give me ebony black tone, but hitherto without success. I have got red, brown, purple, yellow, but never pure clean black. I confess to being a lover of positives on albumenised paper, and solicit your mature advice as to what additional step I should take to gain ebony black tones, with greater permanence.

I prepare and albumenise my own paper (using Canson and Marion's), with chloride of ammonium 10 grains, and then nitrate of silver 60 grains, with 2 drops of acetic acid to each ounce of solution. I print deep, and then immerse in pure water for five minutes, then in solution of strong hyposulphite of soda, with 15 grains of chloride of gold to the pint, adding (per Maxwell Lyte) 2 grains pyrogallic acid. I tone as deep as possible; finish in a fresh solution of hyposulphite of soda; wash for one hour in a running stream of water; immerse in a solution of soda, and two baths of warm water, then finish in a running bath of water for some hours, and then dry, What is superfluous; and what should I further do to gain my wished for colour, &c.?

In the London Photographic Journal for August 21st, 1855, page 210, I find M. Claudet gives a method. for printing positives instantaneously by the bichloride of mercury, and developing with the protosulphate of iron. I have tried the plan, and occasionally get intense ebony black positives with 10 seconds' exposure: But this is not always the case; often the developing solution stains the front and back of pictures; other times the picture is gray, and the whites yellow. It was recommended to fix in the hyposulphite of soda, but this will not do, as the- whole becomes a nasty yellow. This process, I do think, if properly carried out, would give pretty jet black pictures, but the want of chemical and photographic experience and knowledge prevents me knowing the errors in my way; your help is solicited.

[We think your process could be improved in some respects, and the chance of obtaining the tone you desire much improved. In the first place, we think that there should be at least 30 grains of chloride of ammonium, and 120 grains of nitrate of silver to the ounce respectively; this gives greater vigour, and also makes the paper more sensitive. Do not over-print much, and wash all the free nitrate of silver -away, first in pure water, and lastly in weak salt and water before fixing. Tone, before fixing, in bath of 2 grains of chloride of gold to five ounces of water, and soon after the desired tint is obtained, transfer the print to a new hypo. bath of about 1 part to 3 of water; but how long after, experience in the lowering effect of the fixing bath will soon show. After being in the fixing bath for a quarter of an hour at least, remove, and wash in the manner you state above.

We can promise to those who follow this plan, if not absolute black and white, at all events a very near approach to it. Respecting M. Claudet's process with perchloride of mercury, we have had no experience of it, and would gladly receive information on the subject from any of our correspondents who may be wiser than ourselves.